Friday, 1 October 2010 - Monthly Climate Summary for Tasmania - Product code IDCKGC17R0

Tasmania in September 2010: Cold, snow to low levels, flooding and huge waves 

Though few temperature and rainfall records were broken in Tasmania during September, there were many interesting weather events. Huge waves were generated by a deep low on the 16th, snow fell to low levels on several days and heavy rain in the north caused flooding on the 4th. There were several very cold days and nights, and few mild ones.

• Rainfall above average except for the upper east
• Temperatures below average overall
• Westerlies with cold fronts for much of the month

Extremes Maps Records Summaries Important notes the top

Huge waves

The waverider buoy off Cape Sorell on Tasmania’s west coast registered an 18.4 metre wave at about 11 am on the 16th. This approaches the record wave of 19.8 metres measured by a similar buoy operated by CSIRO in July 1985. The peak was a single wave, but for most of the 16th waves at the buoy were averaging over 8 metres. The observers at Maatsuyker Island just off Tasmania’s south coast reported an exceptional 11 metre swell, and at Cape Bruny 10 metres was reported. The huge waves were generated by strong winds around a deep low pressure system over the Southern Ocean south of Tasmania as a cold front swept across the state. The same system brought damaging winds, rain, hail and snow, with road closures, building damage and failed power lines reported across the state. Wind gusts reached 148 km/h at Maatsuyker Island and 141 km/h at Cape Bruny. A few days later the same system brought extreme weather to New Zealand.

Heavy rain and flooding

Heavy rain fell across most of Tasmania on the 4th as a deepening low pressure system approached from the northwest then crossed the state overnight. By 9 am, 15 to 25 mm had fallen in the northwest with light falls elsewhere. The rain continued during the day, with a further 81 mm at Mount Victoria, 75 mm at Mount Barrow and 63 mm at Mount Read during the next 24 hours, causing flooding of most rivers across northern Tasmania. In total, over 50 mm fell in most of the north, west and far south, with near 100 mm on higher ground in the northeast. 

Mostly wet overall

After the heavy rain on the 4th, the weather pattern over Tasmania was nearly always westerly with cold fronts crossing the state regularly. From the 10th it rained every day in the west, and showers extended to most other areas with each front. This meant it was wetter than usual in all but the upper east. Monthly totals graded markedly across the state, from a high of 549 mm at Mount Read in the west to just 18 mm at Swansea in the east. Some areas had nearly double the September average, and Lunawanna (on Bruny Island) had its wettest September since 1984.

Cold days and nights with snow to low levels

There were several very cold days and nights during September. Mount Wellington had the two coldest days for the state so far this year, not rising above -2.2 °C on the 28th and -2.1 °C on the 29th. Liawenee fell to -7.9 °C on the morning of the 7th, equalling the coldest temperature recorded during winter. Liawenee also fell below -7 °C on the 3rd and 8th: never before has it had so many nights this cold in September. Other sites had their coldest September day or coldest night in many years including Dover, which had its coldest September morning on the 8th, and many sites in the south on the 15th. The cold was accompanied by snowfalls to low levels on the 15-16th and 28-29th, something that is uncommon at this time of year and contrasted with a relatively mild winter.

For the whole month, daytime temperatures were mostly one to three degrees cooler than usual in the west and south and slightly cooler than usual elsewhere, while minima were near average. It was the coldest September since at least 2003 for most sites, and Strathgordon had its coolest mean maximum temperature on record for September.

In with the cold weather there were a few days and nights that were warmer than usual, generally when fronts were crossing the state overnight or it was fine during the day. The 20th was especially warm in the north and east with temperatures around 20 °C. Swansea reached 21.7 °C on this day, the warmest temperature in Tasmania for the month, and Devonport reached 19.6 °C, its highest September temperature in 19 years of record. The warmest nights were the 5th, 25th and 27th, when temperatures didn't drop below 10 °C in many areas.

Hobart: wet and windy with many cold nights

It was a wet and windy September in Hobart. A total of 88 mm of rain was recorded for the month, less than the 133 mm that fell last year but still 35 mm more than the long-term average. As with most of Tasmania, the heaviest rain fell on the 4th when 27 mm was recorded in 24 hours. After the westerlies kicked in around the 10th, most days in Hobart were windier than usual, especially on the 15th to 18th and 27-28th. There were three days when gusts exceeded 90 km/h, an equal record for September.

There were many cold nights in Hobart with the temperature dropping below 4 °C ten times, nearly double the normal for September and something that hasn't happened for over 15 years. The coldest temperature was 1.7 °C on the 7th, Hobart's coldest September morning since 1995. There were also a number of cold days, the coldest being 10.5 °C on the 28th (although on the 16th the temperature was below 6 °C for much of the afternoon). The cold was tempered by some warm periods from the 9th to the 12th and 23rd to 26th, so that over the whole month mean temperatures were near normal. The warmest day was 18.9 °C on the 26th and the warmest night was 11.9 °C on the 25th.

Temperatures for the year to date in Hobart are still very warm: the mean daily maximum temperature of 17.9 °C for this period is the highest in over 120 years of record.

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Extremes in September 2010
Hottest day	21.7 °C at Swansea Post Office on the 20th
Warmest days on average	16.3 °C at Bicheno (Council Depot)
Coolest days on average	3.3 °C at Mount Read
Coldest day	-2.2 °C at Mount Wellington on the 28th
Coldest night	-7.9 °C at Liawenee on the 7th
Coolest nights on average	-1.8 °C at Mount Wellington
Warmest nights on average	9.0 °C at Swan Island
Warmest night	12.6 °C at Scamander on the 25th
Warmest on average overall	11.9 °C at Eddystone Point
Coolest on average overall	0.9 °C at Mount Wellington
Wettest overall	549.2 mm at Mount Read
Driest overall	18.4 mm at Swansea Post Office
Wettest day	81.4 mm at Mount Victoria (Una Plain) on the 5th
Highest wind gust	148 km/h at Maatsuyker Island Lighthouse on the 15th

Extremes Maps Records Summaries Important notes the top

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Maps
	Observed	Anomaly	Decile rank
Total rainfall
Mean daily maximum temperatures
Mean daily minimum temperatures

Click on a map to show it full size in a pop-up window

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Highest total September rainfall for at least 20 years
	Total rainfall for September 2010 (mm)	Most recent September at least this wet		Years since wetter	Average for September
Lunawanna	138.4	149.8	in 1984	25	71.2

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Record lowest September mean daily maximum temperature
	Mean daily maximum temperature for September 2010 (°C)	Previous coolest for September		Years of record	Average for September
Strathgordon Village	9.3	9.5	in 1970	28	11.5

Lowest September mean daily maximum temperature for at least 20 years
	Mean daily maximum temperature for September 2010 (°C)	Most recent September at least this cool		Years since cooler	Average for September
Maatsuyker Island Lighthouse	10.2	=10.2	in 1970	40	12.2
Butlers Gorge	8.1	7.9	in 1969	24	10.1

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Record lowest September temperature
	Lowest temperature in September 2010 (°C)		Previous coolest for September		Years of record	Average for September
Dover	-2.1	on the 8th	-1.0	on the 9th in 1992	21	4.9

Extremes Maps Records Summaries Important notes the top

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Summary statistics for September 2010
	Maximum temperatures for September (°C)				Minimum temperatures for September (°C)				Rainfall for September (millimetres)
	Mean for September 2010	Diff from average	Highest for September 2010		Mean for September 2010	Diff from average	Lowest for September 2010		Total for September 2010	Average for September	Rank of September 2010	Fraction of September average
Northern (district 91)
Bridport (Sea View Villas)	14.2	-0.5	19.0	21st	6.1	-0.7	0.6	29th	78.0	76.5	average	102%
Burnie (Round Hill)	14.2	-0.1	19.4	21st	7.4	+0.6	2.3	29th	96.6	87.7	average	110%
Cape Grim BAPS	12.6	-0.8	14.7	12th	8.2	-0.4	4.3	3rd	100.8	77.0	high	131%
Cressy Research Station	14.1	-0.6	19.3	20th	4.0	+0.1	-2.5	8th	57.0	63.8	average	89%
Devonport Airport	14.5	+0.4	19.6	20th	6.4	+0.4	-0.1	30th	85.2	74.9	average	114%
Launceston (Ti Tree Bend)	15.3	-0.2	19.4	20th	5.1	-0.1	-0.6	30th	78.0	67.1	average	116%
Launceston Airport	14.2		18.9	20th	3.7		-2.5	30th	55.0
Low Head	13.5	-0.5	16.8	21st	8.5	+0.1	2.3	30th	86.4	66.7	high	130%
Luncheon Hill (Forestry)	11.0	-1.3	15.2	21st	4.7	-0.7	1.1	29th	192.2	179.6	average	107%
Marrawah			15.1	21st	7.3	-0.1	3.5	3rd	121.4	105.8	average	115%
Scottsdale (West Minstone Road)	13.5	-0.7	18.3	20th	4.5	-0.2	-2.2	30th	128.0	99.5	high	129%
Sheffield School Farm	12.4	-0.7	19.3	20th	4.4	-0.3	-0.9	30th	127.6	128.6	average	99%
Smithton Aerodrome	13.8	-1.0	16.7	21st	5.9	-0.4	-0.6	2nd	116.2	107.1	average	108%
Wynyard Airport	14.4	+0.1	19.2	20th	5.8	+0.9	-0.1	14th	138.2	95.9	high	144%
East Coast (district 92)
Bicheno (Council Depot)	16.3	+0.2	20.0	25th	7.1	-0.3	1.7	8th	21.8	44.4	low	49%
Eddystone Point	16.0	+1.2	20.5	20th	7.9	-0.1	2.1	29th	51.0	63.5	average	80%
Fingal (Legge Street)	14.5	-0.8	20.4	20th	3.0	-0.3	-3.2	30th	22.2	49.6	low	45%
Friendly Beaches	15.9	-0.8	21.3	20th	7.1	-0.4	1.3	8th	27.8	38.0	average	73%
Lake Leake (Elizabeth River)	10.7	-0.6	17.3	20th	1.7	-0.3	-3.8	2nd	53.2	71.0	average	75%
Maria Island (Point Lesueur)	14.4		18.0	25th	7.8		3.2	29th	47.4
Orford (Aubin Court)	14.7	-1.0	19.6	26th	5.7	+0.2	-0.4	8th	54.8	51.9	average	106%
Scamander	16.1	-0.2	19.3	25th	6.5	-0.2	1.2	14th	21.7	54.0	low	40%
St Helens Aerodrome	15.8		21.1	20th	6.4		0.7	14th	21.8
Swan Island	14.0		16.8	21st	9.0		4.0	30th	41.4
Swansea Post Office	16.1	+0.1	21.7	20th	6.3	+0.5	-0.7	8th	18.4	40.9	low	45%
Midlands (district 93)
Ross (The Boulevards)	13.9	-0.5	20.4	20th	3.4	-0.3	-4.6	7th	34.6	53.7	average	64%
Southeast (district 94)
Campania (Kincora)	14.6	-1.7	19.2	12th	5.5	+0.3	-1.5	7th	66.2	50.8	high	130%
Cape Bruny (Cape Bruny)	12.6	-1.8	17.3	9th	6.3	-1.2	2.5	28th	131.4	70.8	v high	186%
Cape Bruny Lighthouse	12.3	-0.9	16.5	9th	6.4	-0.6	2.3	28th	142.8	81.2	v high	176%
Dover	12.8	-1.8	17.6	9th	4.7	-0.2	-2.1	8th	146.0	84.2	high	173%
Geeveston (Cemetery Road)	12.8	-2.0	16.1	25th	5.3	+0.9	-1.2	3rd	152.8	93.4	high	164%
Grove (Research Station)	13.5		17.4	12th	4.1		-3.1	3rd	157.0
Hobart (Ellerslie Road)	14.8	-0.3	18.9	26th	6.6	+0.2	1.7	7th	88.2	53.4	high	165%
Hobart Airport	14.7	-0.6	19.1	12th	6.3	+0.3	0.5	8th	61.4	42.4	high	145%
Maatsuyker Island Lighthouse	10.2	-2.0	13.0	12th	6.3	-0.5	2.6	14th	136.4	109.5	high	125%
Melton Mowbray (North Stockman)	12.8	-1.8	17.5	26th	4.3	-0.1	-2.6	7th	62.2	55.3	average	112%
Mount Wellington	3.8	-0.5	8.1	26th	-1.8	-0.5	-5.6	28th
Tasman Island	11.2		16.6	12th	6.0		0.8	17th	114.8
Tunnack Fire Station	11.3	-1.2	16.5	26th	2.8	-0.5	-4.3	7th	86.8	68.0	high	128%
Derwent Valley (district 95)
Bushy Park (Bushy Park Estates)	14.3	-1.1	18.5	26th	4.2	+0.3	-3.5	8th	106.8	54.3	v high	197%
Maydena Post Office	11.0	-2.7	16.0	21st	3.1	-0.3	-2.0	3rd	179.2	142.2	high	126%
Ouse Fire Station	13.7	-2.1	17.6	12th	4.6	+0.9	-3.9	8th	103.6	75.7	high	137%
Tarraleah Village	9.1	-2.1	13.1	21st	2.0	+0.2	-3.0	3rd	160.9	120.3	high	134%
Central Plateau (district 96)
Butlers Gorge	8.1	-2.0	13.2	7th	1.5	+0.6	-3.8	8th	246.2	169.1	high	146%
Lake St Clair National Park	8.5	-1.5	12.6	7th	0.9	+0.1	-4.9	8th	272.4	216.2	average	126%
Liawenee	7.4		15.6	20th	-0.8		-7.9	7th	70.4	127.4	low	55%
West Coast (district 97)
Hartz Mountain (Keoghs Pimple)	5.9	-2.8	11.8	7th	0.7	-1.1	-2.6	28th	140.2	102.0	high	137%
Mount Read	3.3	-2.2	7.7	4th	-0.6	-1.0	-4.4	29th	549.2	341.3	high	161%
Scotts Peak Dam	9.7	-2.6	15.9	21st	3.2	-1.1	-1.6	8th	310.2	219.3	high	141%
Strahan Aerodrome	12.7	-1.6	15.3	21st	5.9	-0.3	-0.6	3rd	223.8	140.3	high	160%
Strathgordon Village	9.3	-2.2	13.7	21st	3.9	-0.5	-0.5	3rd	462.3	281.1	v high	164%
Warra	8.9		12.8	9th	2.4		-2.7	7th	309.8
King Island (district 98)
King Island Airport	13.7	-0.9	15.5	25th	8.3	0.0	3.7	2nd	74.0	88.3	average	84%
Flinders Island (district 99)
Flinders Island Airport	14.2	-0.9	16.6	4th	8.3	+0.8	-0.1	8th	37.6	63.9	low	59%
Hogan Island	13.2		15.4	12th	8.8		5.3	28th	38.4
Antarctica and Macquarie Island (district 300)
Macquarie Island	4.0	-1.4	6.6	12th	-0.2	-1.7	-6.8	25th	94.0	74.6	high	126%

Extremes Maps Records Summaries Important notes the top

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